diff --git a/NOTICE b/NOTICE
index 2088f264..8ce08359 100644
--- a/NOTICE
+++ b/NOTICE
@@ -52,9 +52,9 @@ OpenAI (MIT License)
 Copyright (c) 2023 OpenAI
 https://github.com/openai/openai-python
 
-PyPDF2 (BSD License)
-Copyright (c) 2006-2008, Mathieu Fenniak
-https://github.com/py-pdf/PyPDF2
+pypdf (BSD License)
+Copyright (c) 2006-2024, pypdf contributors
+https://github.com/py-pdf/pypdf
 
 Requests (Apache 2.0 License)
 Copyright 2019 Kenneth Reitz
diff --git a/README.md b/README.md
index 8e0361c8..db733ffa 100644
--- a/README.md
+++ b/README.md
@@ -205,7 +205,7 @@ The following is a summary of the licenses used by our direct dependencies:
 | SQLAlchemy | MIT     |
 | Pydantic   | MIT     |
 | OpenAI     | MIT     |
-| PyPDF2     | BSD     |
+| pypdf      | BSD     |
 | Requests   | Apache 2.0 |
 | puremagic  | MIT     |
 | filetype   | MIT     |
diff --git a/ROADMAP.md b/ROADMAP.md
index 389693fe..5b1de5e7 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -180,7 +180,7 @@ DocuElevate aims to be the premier open-source intelligent document processing p
 ## Technology Debt
 
 ### Refactoring Needed
-- [ ] Migrate from PyPDF2 to pypdf (modern fork)
+- [x] Migrate from PyPDF2 to pypdf (modern fork) - ✅ Completed 2026-02-12
 - [ ] Standardize error handling across modules
 - [ ] Consolidate configuration management
 - [ ] Optimize database queries
diff --git a/SECURITY_AUDIT.md b/SECURITY_AUDIT.md
index 7b9eac99..36b9d271 100644
--- a/SECURITY_AUDIT.md
+++ b/SECURITY_AUDIT.md
@@ -1,12 +1,51 @@
 # Security Audit Report
 
-**Date:** 2026-02-07  
+**Date:** 2026-02-12  
 **Status:** Bandit Security Scan Completed - All Critical/High/Medium Issues Resolved
 
 ## Executive Summary
 
 This document tracks security vulnerabilities found in DocuElevate and their remediation status. A comprehensive security audit using Bandit has been completed, with all critical, high, and medium severity issues addressed.
 
+## Recent Security Fixes
+
+### CVE-2023-36464: PyPDF2/pypdf Infinite Loop Vulnerability ✅ FIXED (2026-02-12)
+
+**Severity:** Moderate (CVSS: 5.5)  
+**CVE:** [CVE-2023-36464](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-36464)  
+**Advisory:** [GHSA-4vvm-4w3v-6mr8](https://github.com/advisories/GHSA-4vvm-4w3v-6mr8)
+
+**Issue:** Certain versions of PyPDF2 (>=2.2.0, <=3.0.1) and pypdf (prior to 3.9.0) contain a vulnerability where specially crafted PDF files can trigger an infinite loop in `__parse_content_stream`, causing 100% CPU usage and potential denial of service.
+
+**Impact:**
+- **Availability:** High (can block process and consume 100% CPU)
+- **Confidentiality:** None
+- **Integrity:** None
+- **Attack Vector:** Local
+- **Privileges Required:** None
+
+**Remediation:**
+- Upgraded from `PyPDF2>=3.0.0` (vulnerable) to `pypdf>=3.9.0` (fixed)
+- Updated all imports from `PyPDF2` to `pypdf` across the codebase
+- Verified pypdf 6.7.0 installed successfully
+- **Files Updated:**
+  - `requirements.txt` - Updated dependency specification
+  - `app/tasks/process_document.py`
+  - `app/tasks/rotate_pdf_pages.py`
+  - `app/utils/file_splitting.py`
+  - `app/tasks/embed_metadata_into_pdf.py`
+  - `app/tasks/process_with_azure_document_intelligence.py`
+  - `app/views/files.py`
+  - `app/api/files.py`
+  - `tests/test_external_integrations.py`
+  - `tests/test_file_splitting.py`
+
+**Testing:** All affected modules verified for syntax correctness and basic import functionality.
+
+**References:**
+- [py-pdf/pypdf#1828](https://github.com/py-pdf/pypdf/pull/1828) - Fix implementation
+- [py-pdf/pypdf#969](https://github.com/py-pdf/pypdf/pull/969) - Issue introduction
+
 ## Bandit Security Scan Results (2026-02-07)
 
 **Scan Summary:**
@@ -151,7 +190,7 @@ This document tracks security vulnerabilities found in DocuElevate and their rem
 - `MAX_UPLOAD_SIZE`: Maximum file upload size in bytes (default: 1GB)
 - `MAX_SINGLE_FILE_SIZE`: Optional maximum size for a single file chunk
 - **Automatic page-based PDF splitting** for large PDFs when max_single_file_size is configured
-  - Splits PDFs at **page boundaries** using PyPDF2, NOT by byte position
+  - Splits PDFs at **page boundaries** using pypdf, NOT by byte position
   - Each output file is a structurally valid, complete PDF
   - No risk of corrupted or broken PDF files
 - Split files are processed sequentially to prevent overwhelming the system
diff --git a/TODO.md b/TODO.md
index 4042e3cf..cbea172b 100644
--- a/TODO.md
+++ b/TODO.md
@@ -188,7 +188,7 @@ As of this update, DocuElevate uses **automated semantic versioning** via `pytho
 ## 🔧 Technical Debt
 
 ### Refactoring Needed
-- [ ] Replace PyPDF2 with pypdf (modern maintained fork)
+- [x] Replace PyPDF2 with pypdf (modern maintained fork) - ✅ Completed 2026-02-12
 - [ ] Migrate from string-based task names to explicit imports in Celery
 - [ ] Standardize logging format across all modules
 - [ ] Remove duplicated configuration loading code
diff --git a/app/api/files.py b/app/api/files.py
index 7da4f6ac..cad47904 100644
--- a/app/api/files.py
+++ b/app/api/files.py
@@ -460,7 +460,7 @@ def reprocess_with_cloud_ocr(request: Request, file_id: int, db: DbSession):
 
 def _extract_text_from_pdf(file_path: str) -> str:
     """
-    Extract text from a PDF file using PyPDF2.
+    Extract text from a PDF file using pypdf.
 
     Args:
         file_path: Path to the PDF file
@@ -468,11 +468,11 @@ def _extract_text_from_pdf(file_path: str) -> str:
     Returns:
         Extracted text from all pages
     """
-    import PyPDF2
+    import pypdf  # Upgraded from PyPDF2 to fix CVE-2023-36464
 
     extracted_text = ""
     with open(file_path, "rb") as f:
-        pdf_reader = PyPDF2.PdfReader(f)
+        pdf_reader = pypdf.PdfReader(f)
         for page in pdf_reader.pages:
             extracted_text += page.extract_text() + "\n"
     return extracted_text
diff --git a/app/tasks/embed_metadata_into_pdf.py b/app/tasks/embed_metadata_into_pdf.py
index fd8ec487..84dbbbff 100644
--- a/app/tasks/embed_metadata_into_pdf.py
+++ b/app/tasks/embed_metadata_into_pdf.py
@@ -7,7 +7,7 @@ import shutil
 import tempfile
 from pathlib import Path
 
-import PyPDF2  # Replace fitz with PyPDF2
+import pypdf  # Upgraded from PyPDF2 to fix CVE-2023-36464
 
 # Import the shared Celery instance
 from app.celery_app import celery
@@ -128,8 +128,8 @@ def embed_metadata_into_pdf(self, local_file_path: str, extracted_text: str, met
 
         # Open the PDF and modify metadata
         with open(processed_file, "rb") as file:
-            pdf_reader = PyPDF2.PdfReader(file)
-            pdf_writer = PyPDF2.PdfWriter()
+            pdf_reader = pypdf.PdfReader(file)
+            pdf_writer = pypdf.PdfWriter()
 
             # Copy all pages from the reader to the writer
             for page in pdf_reader.pages:
diff --git a/app/tasks/process_document.py b/app/tasks/process_document.py
index 44c0c179..aadc8e33 100644
--- a/app/tasks/process_document.py
+++ b/app/tasks/process_document.py
@@ -6,8 +6,8 @@ import os
 import shutil
 import uuid
 
-import PyPDF2  # Replace fitz with PyPDF2
-from PyPDF2.errors import PdfReadError
+import pypdf  # Upgraded from PyPDF2 to fix CVE-2023-36464
+from pypdf.errors import PdfReadError
 
 from app.celery_app import celery
 from app.config import settings
@@ -343,7 +343,7 @@ def process_document(self, original_local_file: str, original_filename: str = No
     )
     try:
         with open(new_local_path, "rb") as file:
-            pdf_reader = PyPDF2.PdfReader(file)
+            pdf_reader = pypdf.PdfReader(file)
             has_text = False
             for page in pdf_reader.pages:
                 if page.extract_text().strip():
@@ -391,7 +391,7 @@ def process_document(self, original_local_file: str, original_filename: str = No
         )
         extracted_text = ""
         with open(new_local_path, "rb") as file:
-            pdf_reader = PyPDF2.PdfReader(file)
+            pdf_reader = pypdf.PdfReader(file)
             for page in pdf_reader.pages:
                 extracted_text += page.extract_text() + "\n"
 
diff --git a/app/tasks/process_with_azure_document_intelligence.py b/app/tasks/process_with_azure_document_intelligence.py
index 9eab8d39..63aa0282 100644
--- a/app/tasks/process_with_azure_document_intelligence.py
+++ b/app/tasks/process_with_azure_document_intelligence.py
@@ -2,7 +2,7 @@ import logging
 import os
 
 import azure.core.exceptions
-import PyPDF2
+import pypdf  # Upgraded from PyPDF2 to fix CVE-2023-36464
 from azure.ai.documentintelligence import DocumentIntelligenceClient
 from azure.ai.documentintelligence.models import AnalyzeOutputOption, AnalyzeResult
 from azure.core.credentials import AzureKeyCredential
@@ -39,7 +39,7 @@ def get_pdf_page_count(file_path):
     """Get the number of pages in a PDF file."""
     try:
         with open(file_path, "rb") as file:
-            pdf_reader = PyPDF2.PdfReader(file)
+            pdf_reader = pypdf.PdfReader(file)
             return len(pdf_reader.pages)
     except Exception as e:
         logger.error(f"Error getting PDF page count: {e}")
diff --git a/app/tasks/rotate_pdf_pages.py b/app/tasks/rotate_pdf_pages.py
index 4de2f55e..9b21435d 100644
--- a/app/tasks/rotate_pdf_pages.py
+++ b/app/tasks/rotate_pdf_pages.py
@@ -2,7 +2,7 @@ import json
 import logging
 import os
 
-import PyPDF2
+import pypdf  # Upgraded from PyPDF2 to fix CVE-2023-36464
 
 from app.celery_app import celery
 from app.config import settings
@@ -21,7 +21,7 @@ def determine_rotation_angle(detected_angle):
         detected_angle: The angle detected by Azure Document Intelligence
 
     Returns:
-        int: The angle to rotate the page in PyPDF2 (must be multiple of 90 degrees)
+        int: The angle to rotate the page in pypdf (must be multiple of 90 degrees)
     """
     # Normalize angle to be between 0 and 360
     normalized_angle = detected_angle % 360
@@ -35,15 +35,15 @@ def determine_rotation_angle(detected_angle):
     # For angles close to 90, 180, or 270 degrees (±5°), round to nearest 90° increment
     for target in [90, 180, 270]:
         if abs(normalized_angle - target) < 5:
-            # PyPDF2 uses clockwise rotation, so we need to use the complementary angle
+            # pypdf uses clockwise rotation, so we need to use the complementary angle
             rotation_value = (360 - target) % 360
             logger.info(f"Detected angle {detected_angle}° is close to {target}°, will rotate by {rotation_value}°")
             return rotation_value
 
     # For other significant angles, round to nearest 90° increment
-    # (PyPDF2 only supports rotations in 90-degree increments)
+    # (pypdf only supports rotations in 90-degree increments)
     closest_90_multiple = round(normalized_angle / 90) * 90
-    # Convert to PyPDF2 rotation value (clockwise)
+    # Convert to pypdf rotation value (clockwise)
     rotation_value = (360 - closest_90_multiple) % 360
     logger.info(f"Detected angle {detected_angle}° rounded to {closest_90_multiple}°, will rotate by {rotation_value}°")
     return rotation_value
@@ -110,8 +110,8 @@ def rotate_pdf_pages(self, filename: str, extracted_text: str, rotation_data=Non
 
         # Load the PDF
         with open(pdf_path, "rb") as file:
-            pdf_reader = PyPDF2.PdfReader(file)
-            pdf_writer = PyPDF2.PdfWriter()
+            pdf_reader = pypdf.PdfReader(file)
+            pdf_writer = pypdf.PdfWriter()
 
             # Process each page
             for page_idx in range(len(pdf_reader.pages)):
@@ -123,7 +123,7 @@ def rotate_pdf_pages(self, filename: str, extracted_text: str, rotation_data=Non
                     rotation_angle = determine_rotation_angle(detected_angle)
 
                     if rotation_angle > 0:
-                        # PyPDF2 uses clockwise rotation in 90-degree increments
+                        # pypdf uses clockwise rotation in 90-degree increments
                         page.rotate(rotation_angle)
                         logger.info(
                             f"[{task_id}] Page {page_idx+1} rotated by {rotation_angle}° "
diff --git a/app/utils/file_splitting.py b/app/utils/file_splitting.py
index ea501769..f4d08d37 100644
--- a/app/utils/file_splitting.py
+++ b/app/utils/file_splitting.py
@@ -10,7 +10,7 @@ import logging
 import os
 from typing import List, Optional
 
-from PyPDF2 import PdfReader, PdfWriter
+from pypdf import PdfReader, PdfWriter  # Upgraded from PyPDF2 to fix CVE-2023-36464
 
 logger = logging.getLogger(__name__)
 
diff --git a/app/views/files.py b/app/views/files.py
index 862bb2e3..9ec97380 100644
--- a/app/views/files.py
+++ b/app/views/files.py
@@ -492,8 +492,8 @@ def get_original_text(request: Request, file_id: int, db: Session = Depends(get_
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Original file not found on disk")
 
     try:
-        # Extract text from PDF using PyPDF2
-        from PyPDF2 import PdfReader
+        # Extract text from PDF using pypdf
+        from pypdf import PdfReader  # Upgraded from PyPDF2 to fix CVE-2023-36464
 
         reader = PdfReader(file_record.original_file_path)
         text = ""
@@ -532,8 +532,8 @@ def get_processed_text(request: Request, file_id: int, db: Session = Depends(get
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Processed file not found on disk")
 
     try:
-        # Extract text from PDF using PyPDF2
-        from PyPDF2 import PdfReader
+        # Extract text from PDF using pypdf
+        from pypdf import PdfReader  # Upgraded from PyPDF2 to fix CVE-2023-36464
 
         reader = PdfReader(file_record.processed_file_path)
         text = ""
diff --git a/docs/ConfigurationGuide.md b/docs/ConfigurationGuide.md
index 4aaf381d..cdec2742 100644
--- a/docs/ConfigurationGuide.md
+++ b/docs/ConfigurationGuide.md
@@ -58,7 +58,7 @@ MAX_SINGLE_FILE_SIZE=524288000
 **File Splitting Behavior:**
 - When `MAX_SINGLE_FILE_SIZE` is configured and a PDF exceeds this size, it is automatically split into smaller chunks
 - **IMPORTANT:** Splitting is done at **PAGE BOUNDARIES**, not by byte position
-  - Uses PyPDF2 to properly parse PDF structure
+  - Uses pypdf to properly parse PDF structure
   - Each output file is a complete, valid PDF containing whole pages
   - No risk of corrupted or broken PDF files
   - Pages are distributed across output files to stay under size limit
diff --git a/docs/FileDetailPageLayout.md b/docs/FileDetailPageLayout.md
index c7b932db..6ebefb89 100644
--- a/docs/FileDetailPageLayout.md
+++ b/docs/FileDetailPageLayout.md
@@ -15,7 +15,7 @@ POST /api/files/{id}/retry-subtask    → Retry specific task
 ## Text Extraction
 
 Text extraction is performed **on-demand** when the user clicks "View Extracted Text":
-- Uses PyPDF2 to extract text from PDF files in real-time
+- Uses pypdf to extract text from PDF files in real-time
 - Returns JSON: `{"text": "...", "page_count": 3}`
 - Client-side caching prevents re-extraction on subsequent views
 - Loading indicator shown during extraction
diff --git a/docs/UserGuide.md b/docs/UserGuide.md
index a0de2635..64d2c241 100644
--- a/docs/UserGuide.md
+++ b/docs/UserGuide.md
@@ -182,7 +182,7 @@ Both previews support:
 - Full text extraction viewing via modal overlays
 
 **View Extracted Text**: Each preview includes a button to view the complete extracted text in a fullscreen modal. When you click this button:
-- The system extracts text from the PDF file on-demand using PyPDF2
+- The system extracts text from the PDF file on-demand using pypdf
 - A loading indicator shows while extraction is in progress
 - The extracted text is displayed in a scrollable, copy-friendly format
 - The text is cached so subsequent views load instantly
diff --git a/docs/archive/ANALYSIS_SUMMARY.md b/docs/archive/ANALYSIS_SUMMARY.md
index e4512bae..89b55baa 100644
--- a/docs/archive/ANALYSIS_SUMMARY.md
+++ b/docs/archive/ANALYSIS_SUMMARY.md
@@ -230,7 +230,7 @@ httpx>=0.26.0
 
 ### Medium Priority (Next Month)
 - [ ] Fix Pydantic V1 → V2 migration warnings
-- [ ] Migrate from PyPDF2 to pypdf (modern fork)
+- [x] Migrate from PyPDF2 to pypdf (modern fork) - ✅ Completed 2026-02-12
 - [ ] Consolidate storage provider code
 - [ ] Add API pagination
 - [ ] Implement retry logic for Celery tasks
diff --git a/frontend/templates/attribution.html b/frontend/templates/attribution.html
index 8d7e9103..47016dcb 100644
--- a/frontend/templates/attribution.html
+++ b/frontend/templates/attribution.html
@@ -67,9 +67,9 @@
                 <a href="https://github.com/openai/openai-python" class="text-blue-600 hover:underline">https://github.com/openai/openai-python</a>
             </li>
             <li class="mb-2">
-                <span class="font-semibold">PyPDF2</span> (BSD License)<br>
-                Copyright (c) 2006-2008, Mathieu Fenniak<br>
-                <a href="https://github.com/py-pdf/PyPDF2" class="text-blue-600 hover:underline">https://github.com/py-pdf/PyPDF2</a>
+                <span class="font-semibold">pypdf</span> (BSD License)<br>
+                Copyright (c) 2006-2024, pypdf contributors<br>
+                <a href="https://github.com/py-pdf/pypdf" class="text-blue-600 hover:underline">https://github.com/py-pdf/pypdf</a>
             </li>
             <li class="mb-2">
                 <span class="font-semibold">Requests</span> (Apache 2.0 License)<br>
diff --git a/requirements.txt b/requirements.txt
index 2fffd659..1f3ede9e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,7 +6,7 @@ sqlalchemy  # Database ORM
 pydantic  # Data validation
 cryptography>=41.0.0  # Encryption for sensitive settings in database
 openai  # GPT integration for metadata extraction
-PyPDF2>=3.0.0  # PDF processing for text extraction, metadata editing and rotation (replaces PyMuPDF)
+pypdf>=3.9.0  # PDF processing for text extraction, metadata editing and rotation (upgraded from PyPDF2 to fix CVE-2023-36464)
 requests  # HTTP client
 puremagic>=1.25,<2.0  # File type detection (pure Python)
 filetype>=1.2.0,<2.0  # File type detection fallback (pure Python)
diff --git a/tests/test_external_integrations.py b/tests/test_external_integrations.py
index 669fd9aa..30c0166d 100644
--- a/tests/test_external_integrations.py
+++ b/tests/test_external_integrations.py
@@ -778,7 +778,7 @@ class TestPdfGenerator:
     @staticmethod
     def test_generate_default_pdf() -> None:
         """Test that generate_test_pdf creates a valid PDF with embedded text."""
-        import PyPDF2
+        import pypdf  # Upgraded from PyPDF2 to fix CVE-2023-36464
 
         path = generate_test_pdf()
         try:
@@ -786,7 +786,7 @@ class TestPdfGenerator:
             assert os.path.getsize(path) > 100
 
             with open(path, "rb") as f:
-                reader = PyPDF2.PdfReader(f)
+                reader = pypdf.PdfReader(f)
                 assert len(reader.pages) >= 1
                 text = reader.pages[0].extract_text()
                 assert "Invoice" in text
@@ -797,13 +797,13 @@ class TestPdfGenerator:
     @staticmethod
     def test_generate_custom_content_pdf() -> None:
         """Test that generate_test_pdf accepts custom content."""
-        import PyPDF2
+        import pypdf  # Upgraded from PyPDF2 to fix CVE-2023-36464
 
         custom = "Custom test content for verification"
         path = generate_test_pdf(content=custom)
         try:
             with open(path, "rb") as f:
-                reader = PyPDF2.PdfReader(f)
+                reader = pypdf.PdfReader(f)
                 text = reader.pages[0].extract_text()
                 assert "Custom test content" in text
         finally:
diff --git a/tests/test_file_splitting.py b/tests/test_file_splitting.py
index 1ab04c2b..f88460da 100644
--- a/tests/test_file_splitting.py
+++ b/tests/test_file_splitting.py
@@ -12,7 +12,7 @@ import os
 import tempfile
 
 import pytest
-from PyPDF2 import PdfReader, PdfWriter
+from pypdf import PdfReader, PdfWriter  # Upgraded from PyPDF2 to fix CVE-2023-36464
 
 from app.utils.file_splitting import should_split_file, split_pdf_by_size